io	AFRICAN POLITICAL SYSTEMS
emergence of classes the closer they are to one another in culture. A centralized form of government is not necessary to enable different groups of closely related culture and pursuing the same mode of livelihood to amalgamate, nor does it necessarily arise out of the amalgamation. The Nuer have absorbed large numbers of conquered Dinka, who are a pastoral people like themselves with a very similar culture. They have incorporated them by adoption and other ways into their lineage system; but this has not resulted in a class or caste structure or in a centralized form of government. Marked divergencies in culture and economic pursuits are probably incompatible with a segmentary political system such as that of the Nuer or the Tallensi. We have not the data to check this. It is clear, however, that a conquest theory of the primitive state—assuming that the necessary historical evidence is available—must take into account not only the mode of conquest and the conditions of contact, but also the similarities or divergencies in culture and mode of livelihood of conquerors and conquered and the political institutions they bring with them into the new combination.
IX.  The Territorial Aspect
The territorial aspect of early forms of political organization was justly emphasized by Maine in Ancient Law and other scholars have given much attention to it. In all the societies described in this book the political system has a territorial framework, but it has a different function in the two types of political organization. The difference is due to the dominance of an administrative and judicial apparatus in one type of system and its absence in the other. In the societies of Group A the administrative unit is a territorial unit; political rights and obligations are territorially delimited. A chief is the administrative and judicial head of a given territorial division, vested often with final economic and legal control over all the land within his boundaries. Everybody living within these boundaries is his subject, and the right to live in this area can be acquired only by accepting the obligations of a subject. The head of the state is a territorial ruler.
In the other group of societies there are no territorial units defined by an administrative system, but the territorial units are local communities the extent of which corresponds to the range of a particular set of lineage ties and the bonds of direct co-operation.